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XVIII. The Croonian Lecture. — On the Influence exercised by the Movements of 
Respiration on the Circulation of the Blood . By J. Burdon Sanderson, M.D., 
F.B.C.P. Communicated by Dr. Sharpey, Sec. B.S. 
Received December 28, 1866, — Read March 7, 1867. 
Page 
Part I. Previous researches 571 
Part PL. Experiments. — Sect. 1. Description of Apparatus 574 
2. Experiments as to the relation between the thoracic movements, the 
arterial pressure, and the frequency of the contractions of the heart 
in natural respiration 576 
3. Experiments as to the same relation in artificial respiration 1 586 
4. Experiments as to the same relation after section of the pneumogastric 
nerves 589 
Conclusions 592 
Haying in the course of an inquiry relating to the order of cessation of the vital pheno- 
mena in apnoea, the results of which I propose shortly to submit to this Society, been 
led to doubt the truth of the received opinion as to the influence exercised by the 
movements of the chest in respiration on the circulation, and having found that similar 
doubts were entertained by others who had given attention to the subject, I thought 
it necessary before proceeding further to endeavour to obtain a solution of this most 
important question by experiment. 
Part I. — PREVIOUS RESEARCHES. 
It is to Professor Ludwig that we owe the first application of exact methods in the 
investigation of the influence of the thoracic movements on the action of the heart. In 
1846 he performed a series of experiments, the results of which were published the 
following year in Muller’s ‘ Archiv’*. In these experiments he employed an instrument 
(called by him a Kymographion) by which the readings of a hsemadynamometer attached 
to an arterial trunk were inscribed on a cylinder revolving by clockwork at a uniform 
rate. He found that in ordinary respiration the tracing of the kymographion always 
exhibited characters which were distinctive, consisting of large undulations or waves 
produced by the thoracic movements, the contours of which were broken by smaller 
waves expressing the contractions of the heart. As regards the relation between the 
* “ Beitrage zur Kenntniss des Einflusses der Respirationsbewegungen anf den Blutlauf im Aortensysteme,” 
Muller’s Archiv, 1847, p. 242. 
4 I 
MDCCCLXVII. 
